Semiconductor devices, in particular field-effect controlled switching devices such as a junction field effect transistor (JFET), a metal oxide semiconductor field effect transistor (MOSFET) and an insulated gate bipolar transistor (IGBT) are typically used for various applications including but not limited to switches in power supplies and power converters, electric cars, air-conditioners, and inverters in motor drives.
When switching off transistors, switching losses and an overvoltage typically occur between first and second load terminals such as drain and source of an FET or collector and emitter of an IGBT. Since one characteristic of transistors is a specified breakdown voltage Vbr between the first and second load terminals, a goal of transistor design is to avoid electric breakdown caused by overvoltages during turn-off operation over a specified operation temperature range.
Accordingly, there is a need to improve a voltage margin between the specified breakdown voltage Vbr and overvoltages occurring during turn-off operation over a specified operation temperature range without deteriorating switching losses.